Croatica Chemica Acta, Vol. 91 No. 2, 2018.
Original scientific paper
https://doi.org/10.5562/cca3345
Crystal Structure of S-adenosyl-L-homocysteine Hydrolase from Cytophaga hutchinsonii, a Case of Combination of Crystallographic and Non-crystallographic Symmetry
Justyna Czyrko
; Laboratory of Biochemistry and Structural Biology, Institute of Chemistry, University of Bialystok, Poland
Mariusz Jaskolski
; Center for Biocrystallographic Research, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
Krzysztof Brzezinski
orcid.org/0000-0001-9339-7745
; Laboratory of Biochemistry and Structural Biology, Institute of Chemistry, University of Bialystok, Poland
Abstract
The majority of living organisms utilize S-adenosyl-L-homocysteine hydrolase (SAHase) as a key regulator of cellular methylation reactions. The unusual evolution history of SAHase genes is reflected in the phylogeny of these proteins, which are grouped into two major domains: mainly archaeal and eukaryotic/bacterial. Such a phylogeny is in contradiction to the three-domain topology of the tree of life, commonly based on 16S rRNA sequences. Within the latter domain, SAHases are classified as eukaryotic-only or bacterial-only clades depending on their origin and sequence peculiarities. A rare exception in this classification is SAHase from a cellulose-utilizing soil bacterium Cytophaga hutchinsonii (ChSAHase), as the phylogenetic analyses indicate that ChSAHase belongs to the animal clade. Here, the P21212 crystal structure of recombinant ChSAHase in ternary complex with the oxidized form of the NAD+ cofactor and a reaction product/substrate (adenosine) is presented. Additionally, a sodium cation was identified in close proximity of the active site. The crystal contains two translational NCS-related intimate dimers of ChSAHase subunits in the asymmetric unit. Two complete tetrameric enzyme molecules are generated from these dimers within the crystal lattice through the operation of crystallographic twofold axes in the z direction.
This work is licensed under a Creative Commons Attribution 4.0 International License.
Keywords
cellular methylation; S-adenosyl-L-homocysteine (SAH); S-adenosyl-L-methionine (SAM); cellulose degradation; X-ray crystallography; crystallographic symmetry; non-crystallographic symmetry (NCS); translational non-crystallographic symmetry (tNCS)
Hrčak ID:
201344
URI
Publication date:
4.6.2018.
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